Use of streaming media technology (e.g. video/IP, voice/IP) is growing across all market segments, inclusive of consumer, enterprise, and public safety. Today, such media is commonly transported over wired or fixed wireless networks. Advances in wireless broadband technology are enabling such media to also be streamed over next generation wireless broadband networks, such as LTE.
Some communication networks, such as Long Term Evolution (LTE), which is a 4th generation (4G) of radio technologies that comprises a set of enhancements to the Universal Mobile Telecommunications System (UMTS), which is described in a suite of Technical Specifications (TS) developed within and published by the 3rd Generation Partnership Project (3GPP), grant a default bearer to a device upon the device connecting to the network. These default bearers only provide for a “best effort” delivery of all unclassified traffic, inclusive of media streams, with few, if any, guarantees of Quality of Service (QoS). However, some real-time media applications, such as voice, video streaming, etc., need a minimum guaranteed QoS associated with the network bearer used to transport the media in order to present the media to the receiving user with acceptable quality; and to accommodate this need, in addition to providing the default bearer, the network further provides a mechanism that allows requesting an allocation of a bearer having a guaranteed minimum QoS for media transport.
Conventional approaches to bearer reservation attempt to allocate, for a given media stream, a single bearer supporting the required throughput. When the network is congested, however, the allocated bearer may be rescinded. Revocation of the allocated bearer will result in the media stream being redirected to the default bearer, or being blocked altogether, both of which will prove unacceptable to the end user.
Unlike other types of data, the encoded bit rate of streaming media (particularly video) can be varied. That is to say, a sourcing media encoder can vary its output bit rate to match available throughput to a recipient. This allows the quality of the streaming media to gracefully degrade in the presence of network congestion, assuming some feedback mechanism to the encoder is available.
Thus, when an access network becomes congested, there exists a need for a rate control feedback mechanism to vary the bit rate of a stream with the available throughput of the network while still providing the QoS associated with an allocated bearer.